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Physics QUESTION #7062

A plano-convex lens has a diameter of $6 \text{ cm}$ and a thickness at its center of $3 \text{ mm}$. If the speed of light within the lens material is $2 \times 10^8 \text{ m/s}$, calculate the focal length of this lens.

$15 \text{ cm}$
$20 \text{ cm}$
$30 \text{ cm}$✔️
$10 \text{ cm}$

Correct Answer Logic:

1. Calculate Refractive Index ($\mu$):
$\mu = \frac{c}{v} = \frac{3 \times 10^8}{2 \times 10^8} = 1.5$.

2. Determine Radius of Curvature ($R$):
For a lens with radius of aperture $r = 3 \text{ cm}$ and thickness $t = 0.3 \text{ cm}$, the radius of curvature is given by $R \approx \frac{r^2}{2t}$ (for small thickness).
$R = \frac{3^2}{2 \times 0.3} = \frac{9}{0.6} = 15 \text{ cm}$.

3. Lens Maker's Formula:
$\frac{1}{f} = (\mu - 1) \left( \frac{1}{R_1} - \frac{1}{R_2} \right)$. For a plano-convex lens, $R_1 = R$ and $R_2 = \infty$.
$\frac{1}{f} = (1.5 - 1) \left( \frac{1}{15} \right) = 0.5 \times \frac{1}{15} = \frac{1}{30}$.
Thus, $f = 30 \text{ cm}$.

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Professional QUESTION #1830

Question 3302

Under Section 9(2) of the Civil Servants Act 1973, promotions to a non-selection post are made on what basis?

Selection on merit only
Seniority-cum-fitness✔️
Fitness-cum-seniority
Recommendation of the departmental selection board alone

Correct Answer Logic:

Section 9(2)(b) provides that in the case of a non-selection post, promotions shall be made on the basis of seniority-cum-fitness. In contrast, selection posts are filled on the basis of selection on merit under Section 9(2)(a). The distinction between the two criteria is a frequently tested provision.

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Chemistry QUESTION #4354

Question 3303

Consider the balanced chemical equation: $2H_2 + O_2 \rightarrow 2H_2O$. If $4\ g$ of $H_2$ reacts with $32\ g$ of $O_2$ to produce $28\ g$ of $H_2O$, what is the percentage yield of the reaction? (Molar mass of $H_2 = 2\ g/mol$, $O_2 = 32\ g/mol$, $H_2O = 18\ g/mol$)

63.6%
77.8%✔️
87.5%
92.5%

Correct Answer Logic:

Moles of $H_2 = \frac{4}{2} = 2\ mol$. Theoretical yield of $H_2O = 2 \times 18 = 36\ g$. $\% yield = \frac{28}{36} \times 100 = 77.8\%$.

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CISA QUESTION #6827

Question 3304

In evaluating an organization's business continuity plan, an auditor finds that Recovery Time Objective (RTO) is 4 hours but current recovery capabilities require 12 hours. What should be the auditor's PRIMARY recommendation?

Update the BCP document to reflect 12-hour RTO
Assess the gap between RTO requirement and actual capability then develop remediation plan✔️
Reduce RTO to 2 hours
Cancel the BCP

Correct Answer Logic:

When a gap exists between required and actual recovery capabilities, the organization faces unmitigated risk. The auditor should highlight this gap and recommend analysis of whether to: improve capabilities to meet the 4-hour RTO, accept the risk of longer recovery, or adjust business requirements. Simply updating documentation without addressing the gap provides no risk reduction.

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Civil Procedure QUESTION #3713

Question 3305

A contractor agrees to build a deck for a homeowner for $\text{\$10,000}$. Halfway through, the contractor realizes the cost of wood has spiked and tells the homeowner, 'I need an extra $\text{\$2,000}$ to finish, or I'm walking.' The homeowner agrees. After the deck is finished, the homeowner pays only $\text{\$10,000}$. Can the contractor recover the extra $\text{\$2,000}$?

Yes, because the homeowner agreed to the modification.
No, because of the 'pre-existing duty rule.'✔️
Yes, because the price spike was an 'unforeseeable difficulty.'
No, unless the modification was in writing.

Correct Answer Logic:

Under the common law 'pre-existing duty rule,' a promise to pay more for a service the party is already legally obligated to perform is unenforceable for lack of new consideration.

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The Constitution of Pakistan QUESTION #9366

Question 3306

A Judge of a High Court is qualified for appointment under Article 193 if they have been an advocate of a High Court for not less than:

Five years
Ten years✔️
Fifteen years
Twenty years

Correct Answer Logic:

Article 193(2)(a), as amended by the 26th Amendment 2024, provides that a person must have 'for a period of not less than ten years, been an advocate of a High Court.' The same period applies to judicial office under clause (2)(b). The earlier standard set by pre-2024 provisions required different periods.

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Physics and Math QUESTION #783

Question 3307

If $ax^2 + 2hxy + by^2 = 0$, their lines are orthogonal when:

$a + b = 0$✔️
$a - b = 0$
$a = b$
None

Correct Answer Logic:

For the pair of lines $ax^2 + 2hxy + by^2 = 0$ to be perpendicular, the sum of coefficients of $x^2$ and $y^2$ must be zero: $a + b = 0$.

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Islamic Studies QUESTION #653

Question 3308

The battle of Nihawand was fought during the reign of:

Hazrat Abu Bakr
Hazrat Umar✔️
Hazrat Usman
None of these

Correct Answer Logic:

Fought in 642 CE, it was a decisive victory for the Muslims during Hazrat Umar's era.

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Chemistry QUESTION #1073

Question 3309

Which of the following aqueous solutions will exhibit the highest boiling point?

$0.01\text{M}\ \text{Na}_2\text{SO}_4$✔️
$0.015\text{M}\ \text{C}_6\text{H}_{12}\text{O}_6$
$0.01\text{M}\ \text{Urea}$
$0.01\text{M}\ \text{KNO}_3$

Correct Answer Logic:

Boiling point elevation $\propto i \times m$ (van't Hoff factor $\times$ molality). Na$_2$SO$_4$: $i=3$, effective molality $=0.03$. Glucose: $i=1$, $=0.015$. Urea: $i=1$, $=0.01$. KNO$_3$: $i=2$, $=0.02$. Highest: $0.01\text{M}\ \text{Na}_2\text{SO}_4$ with effective particles $=0.03$.

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English QUESTION #8529

Question 3310

The synonym of 'Exemplify' is:

Over
Illustrate✔️
Answer
Summary

Correct Answer Logic:

Exemplify means to illustrate by example.

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Physics QUESTION #7334

Question 3311

A particle of mass $m$ is projected with speed $v$ at $45°$ to the horizontal. When it returns to ground level, the magnitude of the change in momentum is:

$mv\sqrt{2}$✔️
Zero
$2mv$
$\dfrac{mv}{\sqrt{2}}$

Correct Answer Logic:

Initial vertical component: $v_y = v\sin45° = \dfrac{v}{\sqrt{2}}$ (upward)

On landing (by symmetry): $v_y' = \dfrac{v}{\sqrt{2}}$ (downward)

Horizontal component unchanged. Change in momentum:

$|\Delta\vec{p}| = m\left|\Delta v_y\right| = m\cdot\dfrac{2v}{\sqrt{2}} = \mathbf{mv\sqrt{2}}$

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Paper-II (Pharmacognosy and Pharmaceutics-I) QUESTION #3589

Question 3312

Which alkaloid is obtained from 'Atropa belladonna'?

Quinine
Atropine✔️
Morphine
Reserpine

Correct Answer Logic:

Atropine is a tropane alkaloid used as an antispasmodic and mydriatic.

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Dairy Food Science and Technology QUESTION #5927

Question 3313

The minimum required protein content of yoghurt in most standards is typically achieved by:

Adding sodium caseinate
Fortifying with skim milk powder (SMP) or whey protein concentrate (WPC) to increase total MSNF✔️
Increasing fermentation time
Reducing the fat content

Correct Answer Logic:

To ensure proper gel formation and meet protein standards ($\geq 2.7\text{–}3.2\%$ protein), milk is often standardized by adding SMP or WPC to increase total MSNF. This also improves texture, body, and reduces syneresis.

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General Knowledge QUESTION #8887

Question 3314

What was the profession of Mohtarma Fatima Jinnah?

Doctor
Lawyer
Dentist✔️
Economist

Correct Answer Logic:

Fatima Jinnah was a dentist.

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Chemistry QUESTION #5542

Question 3315

For a first-order reaction, 32% of the reactant remains after 570 s. Calculate the rate constant $k$ (in $\times10^{-3}\ s^{-1}$, rounded to nearest integer). [Given: $\log_{10}2 = 0.301$, $\ln 10 = 2.303$]

3✔️
2
1
4

Correct Answer Logic:

For first-order: $k = \frac{2.303}{t}\log\frac{[A]_0}{[A]} = \frac{2.303}{570}\log\frac{100}{32} = \frac{2.303}{570}\log\left(\frac{25}{8}\right)$. $\log\frac{25}{8} = \log 25 - \log 8 = (2\log 5)-(3\log 2) = 2(1-0.301)-3(0.301) = 2(0.699)-0.903 = 1.398-0.903 = 0.495$. $k = \frac{2.303\times0.495}{570} = \frac{1.14}{570} \approx 2\times10^{-3}\ s^{-1}$. Nearest integer = $2\times10^{-3}\ s^{-1}$.

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Math Physics Chemistry Biology QUESTION #4333

Question 3316

Reversible inhibitors differ from irreversible inhibitors because they:

Bind permanently and cannot be removed
Bind temporarily and can be removed✔️
Permanently inactivate the enzyme
Change enzyme structure permanently

Correct Answer Logic:

Reversible inhibitors bind through weak, non-covalent interactions and can be removed, restoring enzyme activity. Irreversible inhibitors form permanent covalent bonds with the enzyme.

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Nursing QUESTION #9160

Question 3317

In nursing management, Management by Objectives (MBO) was developed by:

Frederick Taylor
Peter Drucker✔️
Abraham Maslow
Douglas McGregor

Correct Answer Logic:

Management by Objectives (MBO) was introduced by Peter Drucker in his 1954 book The Practice of Management. MBO is a process where:

Managers and employees jointly set specific, measurable objectives
Performance is evaluated against these pre-set objectives
Feedback and appraisal are systematic

In nursing management, MBO helps Head Nurses set clear performance targets for nursing staff, improving accountability and service quality. Other options: Frederick Taylor — Scientific Management; Maslow — Hierarchy of Needs; McGregor — Theory X and Y.

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Chemistry QUESTION #467

Question 3318

__________ is necessary for development of leaves and it tends to accumulate in leaves and bark.

NO?
Calcium✔️
Gypsum
Nitrogen

Correct Answer Logic:

Calcium accumulates in leaves and bark

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Urdu QUESTION #1403

Question 3319

''آثارالصنادید'' کس کی کتاب ہے؟

سر سید احمد خان✔️
مرزا غالب
مولانا حالی
ڈپٹی نذیر احمد

Correct Answer Logic:

''آثارالصنادید'' سر سید احمد خان (1817–1898) کی تاریخی و آثارِ قدیمہ کی مشہور کتاب ہے جو 1847 میں شائع ہوئی۔ اس میں دہلی کی تاریخی عمارتوں، یادگاروں اور مشاہیر کا تفصیلی تذکرہ ہے۔ اس کتاب نے سر سید کو علمی حلقوں میں پہلی بڑی شہرت دلائی۔

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Civil Engineering QUESTION #6583

Question 3320

The dry density of a moist soil sample in relation to its bulk density is:

Greater than the bulk density
Equal to the bulk density
Less than the bulk density✔️
No specific relationship exists

Correct Answer Logic:

Bulk density $\rho_b = \dfrac{M_{total}}{V}$ includes the mass of water. Dry density $\rho_d = \dfrac{M_{solids}}{V}$. Since $M_{total} > M_{solids}$, dry density is always less than bulk density for any moist soil.

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